A polymer formed article such as a plastic film is inexpensive and exhibits excellent workability. Therefore, such a polymer formed article is provided with a desired function, and used in various fields.
For example, a gas barrier plastic film that prevents permeation of water vapor and oxygen is used as a food/drug packaging film in order to suppress oxidation and denaturation of proteins, oils, fats, and the like to keep the taste and freshness.
In recent years, use of a transparent plastic film as an electrode substrate instead of a glass sheet has been proposed for displays (e.g., liquid crystal display and electroluminescence (EL) display) in order to implement a reduction in thickness, a reduction in weight, an increase in flexibility, and the like. However, since a plastic film tends to allow water vapor, oxygen, and the like to pass through as compared with a glass sheet, the elements provided in the display may deteriorate.
In order to solve this problem, Patent Document 1 discloses a flexible display substrate in which a transparent gas barrier layer formed of a metal oxide is stacked on a transparent plastic film.
However, since the transparent gas barrier layer formed of a metal oxide is stacked on the surface of the transparent plastic film by vapor deposition, ion plating, sputtering, or the like, cracks may occur in the gas barrier layer when the substrate is rounded or folded, so that the gas barrier capability may deteriorate.
Patent Document 2 discloses a method of producing a gas barrier film that includes forming a polysilazane film on at least one side of a film, and subjecting the polysilazane film to a plasma treatment. However, this method has a problem in that a sufficient gas barrier capability cannot be obtained if the thickness of the gas barrier layer is not of the order of micrometers. For example, Patent Document 2 discloses that the water vapor transmission rate is 0.50 g/m2/day when the gas barrier layer has a thickness of 0.1 μm.